Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income Tax Expense (Benefit)	$ 10.5	$ 14.7	$ 32.6	$ 35.4
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss at beginning of period			2,536.6
Accumulated other comprehensive loss at end of period	$ 2,892.2		$ 2,892.2